1. Field of the Invention
This invention relates to improvements in methods and apparatus for heating of sterile surgical liquids. More specifically, this invention relates to devices used to keep sealed containers of sterile surgical liquids at or near a desired temperature above the ambient air temperature of the room. These devices may work in conjunction with another heating system to maintain an elevated temperature of surgical fluids in an open container such as a basin or cavity formed in a sterile drape.
2. Background of the Invention
Devices for the heating of sterile surgical liquids are known in the art. In a wide variety of surgical procedures, sterile fluids are used to irrigate the site of the surgery. It is important that the temperature of the fluids used be strictly controlled. As the portion of the brain that regulates body temperature is shut down with anesthesia, it is important that the introduction of sterile fluids does not cool the body core temperature. Clinical studies have indicated that a range of adverse consequences arise from a change in body core temperature as little as one to three degrees Celsius. The adverse consequences from mild perioperative hypothermia include hypertension and increased vascular resistance, cardiac events, coagulopathy, an increase risk of surgical wound infections, and delays in the body's ability to remove drugs from its systems. An additional potential adverse consequence is shivering that may increase metabolic rate up to 500% and thus increase demands for oxygen and the need to clear carbon dioxide. This list of complications is by no means exhaustive, but it highlights the critical importance in controlling the body core temperature. Careful control of the temperature of sterile irrigation fluids is an important part of controlling body core temperature.
Co-pending and commonly assigned U.S. patent application Ser. No. 11/209,283 for Liquid Warming Device with Basin discloses various apparatus configurations and control schemes to precisely control the temperature of a sterile fluid in an open container such as a surgical basin or a surgical drape covering a cavity in a fluid warming device.